Malaria transmission in the coastal zone and in the Centre of Côte d'Ivoire during the dry season

Background: Malaria remains a threat in sub-Saharan Africa, particularly in Côte d'Ivoire, where it is endemic and represents the leading cause of hospital consultations, morbidity and mortality. The strong climatic variations that exist between coastal and savannah areas of Côte d'Ivoire suggest that vector control interventions should be scheduled according to the eco-epidemiological diversity. This study evaluates bioecological parameters of vectors and malaria transmission in two health districts, one coastal and one central of Côte d'Ivoire.

Methods: The study was conducted in the coastal (Jacqueville) and savannah (Béoumi) areas of Côte d'Ivoire from November 2018 to March 2019. Human Landing Catches (HLC) were conducted monthly at the study sites to determine Anopheles vector species composition, biting behaviour as well as entomological parameters of malaria transmission. Mosquitoes were collected over 12 h, from 6:00 pm to 6:00 am during 2 days per month. Mosquitoes infectivity was revealed by enzyme-linked immunosorbent assay (ELISA) for Plasmodium falciparum circumsporozoite protein. A random sample of 100 Anopheles gambiae sensu lato (s.l.) including all CSP-positive females, were further classified by polymerase chain reaction (PCR) at the species and molecular form levels.

Results: In Jacqueville, 853 (99.7%) An. gambiae s.l., and 3 (0.35%) Anopheles pharoensis were collected. In Béoumi, 811 (96.3%) An. gambiae s.l., 23 (2.73%) Anopheles funestus and 8 (0. 95%) An. pharoensis have been found. Anopheles coluzzii represented the only species of the An. gambiae complex in Jacqueville. Among the An. gambiae s.l. samples tested in Beoumi, 29 (58%) were An. coluzzii and the rest 21 (42%) was An. gambiae sensu stricto. The human biting rate (HBR) in Jacqueville increased from 5.7 (b/p/n) in November to 17.3 (b/p/n) in March. Conversely in Béoumi the HBR decreased from 16.4 (b/p/n) in November to 0.69 (b/p/n) in March. In Jacqueville, the entomological inoculation rate (EIR) varies from 0.21 to 0.56 (ib/p/n) with the pic of 0.56 (ib/p/n) in February. In Béoumi no infection was detected in the parous An. gambiae s.l. samples tested during the study period.

Conclusions: This study evaluates bioecological parameters of vectors and malaria transmission in two health districts, one coastal and one central of Côte d'Ivoire.